Marc
It's not a dead lock situation... AFAIK anyhow. I changed all the code (2
days ago), specifically the update balance code, which may cause deadlock
and I still have the problem. So I guess these the deadlock messages are off
the topic and a hang over from when I was wondering if the LOCKING-WAITING
(TRANSACTION) was caused by deadlock.
BTW I am busy corresponding with Simon to see if I can get my code to run
with the latest CVS version.
I'll let y'all know the results.
> -----Original Message-----
> From: marc fleury [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, January 31, 2001 11:40 AM
> To: jBoss
> Subject: RE: [jBoss-User] LOCKING-WAITING (TRANSACTION)
>
>
> so wait, I am confused... is this a deadlock situation?
> or is it a JBoss passivation bug?
>
>
> marc
>
> |-----Original Message-----
> |From: [EMAIL PROTECTED]
> |[mailto:[EMAIL PROTECTED]]On Behalf Of Nortje, Andrew
> |Sent: Wednesday, January 31, 2001 7:23 AM
> |To: 'jBoss'
> |Subject: RE: [jBoss-User] LOCKING-WAITING (TRANSACTION)
> |
> |
> |Thanks Ole. Always something interesting to learn out there.
> |
> |> -----Original Message-----
> |> From: Ole Husgaard [mailto:[EMAIL PROTECTED]]
> |> Sent: Wednesday, January 31, 2001 8:00 AM
> |> To: jBoss
> |> Subject: Re: [jBoss-User] LOCKING-WAITING (TRANSACTION)
> |>
> |>
> |> Hi,
> |>
> |> "Nortje, Andrew" wrote:
> |> > OK I got it figured. I got the dead lock situation that Ole
> |> sketched. BTW if
> |> > anyone is dealing with accounts and account balances NEVER
> |> update the
> |> > account balance when you are inserting line items, you are
> |> sure to get
> |> > deadlock. Only update the balance once in a while, or when
> |> necessary (e.g.
> |> > when the customer wants to withdraw funds), from
> |> information in the account
> |> > line items.
> |>
> |> One way to get around such deadlocks is by
> |> ordering access to you beans within
> |> transactions.
> |>
> |> For example, if you have entity beans Account
> |> and AccountLine, with instances account and
> |> accountLine, you can get around the deadlock
> |> if you always access account first when you need
> |> to access both instances.
> |>
> |> The following two threads might deadlock:
> |> 1: accountLine.getAmount(...);
> |> account.updateBalance(...);
> |> 2: account.getBalance(...);
> |> accountLine.getAmount(...);
> |>
> |> But if Account is always accessed first, no
> |> deadlock:
> |> 1: account.getBalance(...);
> |> accountLine.getAmount(...);
> |> account.updateBalance(...);
> |> 2: account.getBalance(...);
> |> accountLine.getAmount(...);
> |>
> |> The extra call in thread 1 above ensures that
> |> the account is locked first. And if the account
> |> is always locked first when you need to lock
> |> both account and accountLine, the deadlock
> |> scenario I described cannot happen (at least
> |> not between these two beans).
> |>
> |>
> |> Best Regards,
> |>
> |> Ole Husgaard.
> |>
> |>
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